Preparation of dinitro alcohols

ABSTRACT

A METHOD FOR PREPARING DINITRO ALCOHOLS HAVING AT LEAST 4 CARBON ATOMS BY HETING A VICINAL NITROALKYL NITRATE HAVING AT LEAST 4 CARBON ATOMS AT A TEMPERTURE OF AT LEAST 100*C. THE DINITRO SO PREPARED CORRESPOND TO THE FORMULAS:   R-C(-R1)(-NO2)-C(-R2)(-R8)-C(-R3)(-R7)-C(-R4)(-OH)-   R-C(-R1)(-NO2)-C(-R2)(-R6)-C(-R3)(-NO2)-C(-R4)(-R5)-OH AND ARE USEFUL AS SOLVENTS, PLASTICIZERS, BACTERICIDES, LUBRICANTS AND FUEL ADDITIVES.   C(-R4)(-R5)-NO2

3,579,594 Patented May 18, 1971 3,579,594 PREPARATIUN OF DINITRO ALCOHOLS John M. Larkin, Hopewell Junction, N.Y., assignor to Texaco Inc., New York, N.Y. No Drawing. Filed Nov. 30, 1967, Ser. No. 686,820 Int. Cl. C07c 79/18, 87/04 US. Cl. 260-632 14 Claims ABSTRACT OF THE DISCLOSURE A method for preparing dinitro alcohols having at least 4 carbon atoms by heating a vicinal nitroalkyl nitrate having at least 4 carbon atoms at a temperature of at least 100 C. The dinitro alcohols so prepared correspond to the formulas:

and are useful as solvents, plasticizers, bactericides, lubricants and fuel additives.

This invention relates to a novel method of preparing multifunctional organic compounds from nitroalkyl nitrates. In particular, it relates to a method for preparing dinitro alcohols by thermal rearrangement of vicinal nitroalkyl nitrates.

In the past, preparation of dinitro alcohols has been accomplished by base catalyzed condensation of alphabeta unsaturated carbonyl compounds, such as acrolein and methyl vinyl ketone, with nitroparaffins, such as nitromethane. Although such base catalyzed condensation reactions produced the corresponding dinitro alcohol, the product sought was formed in relatively poor yields and in admixture with other materials such as nitroaldehydes and olefinic nitroalcohols which presented isolation and purification difficulties. Moreover, by employing costly generally not readily available nitroparaflins as starting materials, the process became commercially unattractive.

A method has now been found whereby dinitro alcohols can be produced in substantially higher yields in admixture with minor amounts of simple nitroolefins and alcohols which permit processing Without the necessity of utilizing complicated and expensive purification procedures.

Broadly, this invention contemplates a method of preparing a dinitro alcohol having at least 4 carbon atoms which comprises providing a vicinal nitroalkyl nitrate having at least 4 carbon atoms and heating said vicinal nitroalkyl nitrate to a temperature of at least 100 C.

According to this invention, the contemplated dinitro alcohols correspond to the formula:

and *1 R R R R R I l ater-t N02 R R OH N02 where the R and R groups are hydrogen or alkyl. Groups such as carboxyl, alkoxy, sulfoxide, sulfone, phenoxy or halogen, alone or in combination may be present in place of hydrogen, preferably as a substituent on the above-mentioned alkyl groups.

Vicinal nitroalkyl nitrates contemplated as starting materials in the instant invention include for example l-nitro- 2,4,4-trimethyl-2-pentyl nitrate, 3-nitro-2,4,4-trimethyl-2- pentyl nitrate, 1-nitro-2-methyl-2-pentyl nitrate, l-nitro-2- methyl-Z-hexyl nitrate, 1-nitro-4-methyl-2-pentyl nitrate, l-nitro-Z-pentyl nitrate, 1-nitro-2-hexyl nitrate, mixtures of 4-nitro-5-nonyl nitrate and 5-nitro-4-nonyl nitrate, lnitro-2-dodecyl nitrate, mixtures of 7-nitro-8-pentadecyl nitrate and 8-nitro-7-pentadecyl nitrate, 1-nitro-2-octadecyl nitrate, mixtures of 3-nitro-4-eicosyl nitrate and 4-m'tro-3-eicosyl nitrate, 1-nitro-2-docosyl nitrate, Z-nitrol-butyl-l-cyclopentyl nitrate, 1-carboxy-9-nitro-10-octa decyl nitrate and l-carboxy-10-nitro-9-octadecyl nitrate. Mixture of vicinal nitroalkyl nitrates is similarly contemplated.

The vicinal nitroalkyl nitrates thermally rearranged to dinitro alcohols in accordance with this invention may be prepared by the procedure described in U.S. Pat. 3,282,983. According to this procedure an alkene is contacted simultaneously With dinitrogen tetroxide and oxygen at a temperature between -40 to 20 C. to form a nitroalkyl peroxynitrate. The intermediate nitroalkyl peroxynitrate is thereafter contacted with a reducing agent at a temperature of between 20 and 30 C. to form the vicinal nitroalkyl nitrate. The vicinal nitroalkyl nitrate precursor contemplated in the instant invention corresponds to the formula:

Where the R, R R and R groups are hydrogen or alkyl and at least one of said groups is alkyl, where the nitrate has a chain of 4 carbon atoms adjacent the nitrate group and further where the fourth carbon atom has an available hydrogen atom attached thereto. Carboxy, alkoxy, sulfoxide, sulfone, phenoxy or halogen groups, alone or in combination may be present in the precursor, preferably as a substituent on the above mentioned alkyl groups.

Thermal rearrangement of the vicinal nitroalkyl nitrate precursor employed in the instant invention to the dinitro alcohol is accomplished by heating at a temperature of at least C. up to a temperature of approximately 500 C. and preferably from about C. to 250 C. for periods ranging from about a few seconds (about 2 seconds) to 24 hours or longer. Associated with the rearrangement is the formation under the conditions prescribed above, particularly when operating at elevated temperatures, of minor amounts of resinous by-product which is easily separated from the desired product. In a preferred embodiment resinous byproduct formation may be substantially reduced by conducting the reaction in the presence of a liquid medium inert to the rearrangement. Appropriate media include a wide range of hydrocarbons including heptane, octane, nonane, dodecane, benzene, toluene, xylene, orthodichlorobenzene, chlorobenzene, diphenyl ether, perhalogenated alkanes where the halogen is fluorine and chlorine and in general any organic medium not adversely affecting dinitro alcohol formation. In a highly preferred embodiment, thermal rearrangement is carried out in the aforementioned medium comprising from 0.5 to 50 weight percent nitrate preferably at concentrations ranging from about 2 to about 15 weight percent.

Specific examples of thermally rearranged vicinal nitroalkyl nitrates to the dinitro alcohol prepared according .to the inventive process include 1,5-dinitro-2,4,4-trimethyl-2pentanol, 3 ,5 -dinitro-2,4,4-trimethyl-Z-pentanol, 1,5 -dinitro-2-methyl-2-pentanol,

1,5 -dinitro-2-methyl-2-hexanol, 1,5-dinitro-4-methyl-2-pentanol,

1,5 -dinitro-2-pentanol,

1,5 -dinitro-2-hexanol, 3,5-dinitro-2-methyl-2-pentanol, 1,5-dinitro-2-decanol,

and a mixture of dinitrohydroxystearic acids.

When the vicinal nitroalkyl nitrate is heated in accordance with the procedure described above the product is a dinitro alcohol where the hydroxy group is on the carbon atom originally bearing the nitrate and a nitro group is positioned on a carbon atom 3 atoms away. The original vicinal nitro group is now vicinal to the hydroxy group in its original position.

The method of the invention, for purposes of illustration and visualization, is further explained by the following equations:

where the R, R R R R R R R and R groups are hydrogen or alkyl.

The dinitro alcohols prepared according to this invention are useful as solvents, plasticizers, bactericides, lubricants and fuel additives. Further, they are useful as intermediates in the preparation of diamino alcohols, dinitroalkyl esters and others and nitro and amino carboxylic acids.

In order to more fully illustrate the nature of our invention and manner of practicing the same the following examples are presented.

EXAMPLE 1 To a solution of 5.6 grams (0.05 mole) of 2,4,4-trimethyl-l-pentene in 55 milliliters of carbon tetrachloride maintained at C. there was simultaneously added over a period of 4% hours 3.1 milliliters (0.05 mole) of dinitrogen tetroxide and 60.5 milliliters per minute of oxygen. The system was thereafter fiushed with nitrogen and the flask contents cooled to approximately to -10 C. Nitric oxide was bubbled through the solution at the rate of 60.5 milliliters per minute for 22 minutes. The resulting blue-green solution was stirred at approximately 10 C. for an additional minutes. The solvent was subsequently removed under vacuum at room temperature. 10.79 grams of 1-nitro-2,4,4-trimethyl-2-pentyl nitrate was recovered.

A solution of 2 grams of 1-nitro-2,4,4-trimethyl-Z-pentyl nitrate in 50 milliliters of an inert medium consisting of a linear polymer having a molecular weight of 755 with repeating CF CFCl units was heated at 112 C. for 17 hours. The resulting light amber liquid was cooled and extracted with 45 and 20 milliliters portions of methanol. After evaporating off the methanol under vacuum a twophase liquid system remained which was chromatographed on 16 grams of silica gel. The excess diluent was eluted with a percent methylene chloride-75 percent isohexane solution. From 85 milliliters of 100 percent methylene chloride there was obtained 0.467 gram of a yellow liquid indicated by infrared to be 1,S-dinitro-2,4,4-trimethyl-2- pentanol. Another eluant of 150 milliliters of a 20 percent ether-8O percent methylene chloride solution provided 0.977 gram of viscous yellow liquid also indicated by infrared to be the above dinitropentanol.

EXAMPLE 2 5.6 grams (0.05 mole) of 2,4,4-trimethyl-2-pentene in 55 milliliters of carbon tetrachloride was treated with dinitrogen tetroxide and oxygen, followed by nitric oxide reduction as in Example 1. The product was indicated by infrared to be 3-nitro-2,4,4-trimethyl-Z-pentyl nitrate. The yield of product was 10.64 grams.

A solution of 6 grams of crude 3-nitro-2,4,4-trimethyl- 2-pentyl nitrate in 150 milliliters of the medium employed in the Example 1 was heated at a temperature of from 110 to 112 C. for 16 hours. After cooling the solution was extracted with two milliliters portions of methanol. The combined methanol extracts were evaporated under vacuum leaving a two-phase liquid syste The liquid was chromatographed on 35 grams of silica gel. The inert medium was eluted with 25 percent methylene chloride-75 percent isohexane solution and thereafter with methylene chloride-ether solutions. A total of 4.13 grams of 3,5- dinitro-2,4-trimethyl-2-pentanol was recovered and identified by infrared,.

EXAMPLE 3 A solution of 3.5 grams of 1-nitro-2-methyl-2-pentyl nitrate in milliliters of the medium employed in Example 1 was heated at C. for one-half hour, at to C. for one-half hour, and finally at to 128 C. for 2% hours. The dinitro alcohol and unconverted nitrate were extracted in accordance with the procedure of the preceding examples. A total of 1.44 gram of a product identified by infrared to be 1,5-dinitro-2-methyl-2- pentanol was obtained.

EXAMPLE 4 A solution of 2.75 grams of 1-nitro-2-methy1-2-hexy1 nitrate was heated in 80 milliliters of the medium employed in Example 1 at 128 C. for 2% hours. The product was identified as 1,5-dinitro-2-methyl-2-hexanol.

EXAMPLE 5 A solution of 2 grams of 1-nitro-4-methyl-2-pentyl nitrate in 90 milliliters of ortho-dichlorobenzene was heated rapidly to reflux and held at 179 to 180 C. for 10 minutes. A conversion of 95 percent and a yield of 83 percent of the dinitro alcohol, 1,5-dinitro-4-methyl-2- pentanol, was obtained after distilling ofl? the bulk of the solvent under vacuum and removing the remainder of the solvent by pentane extraction. The dinitro alcohol above was similarly obtained by heating the above vicinal nitro nitrate at 200 C. in the absence of a medium for 2 minutes.

EXAMPLE 6 A 10 percent solution of 1-nitro-2-penty1 nitrate in ortho-dichlorobenzene was heated at 173 to 176 C. for 20 minutes. The medium was removed by vacuum distillation and an 80 percent yield of 1,5-dinitro-2-pentanol was obtained.

EXAMPLE 7 A solution of 4.55 grams of 2-methy1-3-nitro-2-penty1 nitrate in 175 milliliters of chlorobenzene was heated at a reflux temperature of C. under nitrogen for 3 hours. The solution was cooled and the medium distilled off at 31-34" C. at 10 mm. pressure. A yield of 2.89 grams of light brown liquid residue Was indicated 'by infrared to be 3,5-dinitro-2-methyl-2-pentanol.

EXAMPLE 8 A solution of 6.00 grams of 1-nitro-2-hexyl nitrate in 100 milliliters of dichlorobenzene was heated at reflux (176-179 C.) under nitrogen for 18 minutes. The solution was cooled and the medium distilled off at 108-117 C, at 80-85 mm. pressure. Chromatographic analysis of the brown liquid showed 1,5-dinitro-2-hexanol.

5 EXAMPLE 9 20 grams (0.071 mole) of oleic acid and 55 cc. of carbon tetrachloride were mixed and cooled to C. Oxygen, at the rate of 60 milliliters per minute, and nitrogen dioxide (0.14 mole) were simultaneously introduced over a period of 4% hours. The mixture was subsequently flushed with nitrogen and nitric oxide was introduced at the rate of 60.8 milliliters per minute for 45 minutes at a temperature of from 5 to 4 C. The volatiles were thereafter removed and 26.8 grams of a nitronitratostearic acid was recovered.

11.05 grams of the nitrate in 150 milliliters of orthodichlorobenzene was heated at 162174 C. for 24 minutes under a nitrogen atmosphere, The solution was cooled and the solvent distilled off at 9 mm. pressure. A yield of 10.60 grams of dark liquid was identified by infrared to be a mixture of dinitrohydroxystearic acids.

EXAMPLE 10 To a solution of 60 grams of polybutene having an average molecular weight of 940 in 120 milliliters of chlorobenzene at 0-4 C. there was added 5.2 grams of gaseous N0 in a stream of oxygen (65 ml./min.) for a period of 4 /2 hours. Infrared analysis indicated this product to be a vicinal nitro nitrate. The solution was thereafter heated at a reflux temperature of 1141l7 C. in a nitrogen atmosphere for 2% hours. The chlorobenzene was removed by distilling at reduced pressure of 50 mm, while nitrogen was bubbled through the solution maintained at 70 C. 63.5 grams of yellow liquid product was identified by infrared to be the dinitro alcohol of a polybutene of 940 average molecular weight.

I claim:

1. A method of preparing a dinitro alcohol having at least 4 carbon atoms which comprises heating at a temperature of from 100 to 500 C. for a period of two seconds to 24 hours in an inert liquid medium, a vicinal nitroalkyl nit-rate wherein said nitrate has a chain of at least 4 carbons adjacent to the nitrato group and further where the fourth carbon atom adjacent to said nitrate group has an available hydrogen atom attached thereto.

2. A method according to claim 1 wherein said heating is conducted at a temperature of from 110 C. to 250 C.

3. A method according to claim 1 wherein said heating is conducted in the presence of an inert medium which contains from about 0.5 to 50 weight percent of said nitrate.

4. A method according to claim 1 wherein said medium is a hydrocarbon.

5. A method according to claim 1 wherein said medium is a linear polymer having a molecular weight of 775 with repeating CF CFCl units.

6'. A method according to claim 1 wherein said medium is dichlorobenzene.

7. A method in accordance with claim 1 wherein said vicinal nitroalkyl nitrate is 1-nitro-2,4,4-trimethyl-2- pentyl nitrate and said dinitro alcohol is 1,5-dinitro-2,4, 4-trimethyl-2-pentanol.

8. A method in accordance with claim 1 wherein said vicinal nitroalkyl nitrate is 3-nitro-2,4,4-trimethyl-2- pentyl nitrate and said dinitro alcohol is 3,5-dinitro-2,4, 4-trimethyl-2-pentanol.

9. A method in accordance with claim 1 wherein said vicinal nitroalkyl nitrate is 1-nitro-2-methyl-2-pentyl nitrate and said dinitro alcohol is 1,5-dinitro-2-methyl-2- pentanol.

10. A method in accordance with claim 1 wherein said vicinal nitroalkyl nitrate is 1-nitro-2-methyl-2-hexyl nitrate and said dinitro alcohol is 1,5-dinitro-2-methyl-2- hexanOl,

1 1. A method according to claim 1 wherein said vicinal nitroalkyl nitrate is l-nitro-2-pentyl nitrate and said dinitro alcohol is 1,5-dinitro-2-pentanol.

12. A method according to claim 1 wherein said vicinal nitroalkyl nitrate is 2-methyl-3-nitro-2-pentyl nitrate and said dinitro alcohol is 3,5-dinitro-2-methyl-2-pentanol.

' 13. A method in accordance with claim 1 wherein said vicinal nitroalkyl nitrate is 1-nitro-2-pentyl nitrate and said dinitro alcohol is 1,5-dinitro-2-pentanol.

14. A method in accordance with claim 1 wherein said vicinal nitroalkyl nitrate is 1-nitro-4-methy1-2-pentyl nitrate and said dinitro alcohol is 1,5-dinitro-4-methyl-2- pentanol.

References Cited UNITED STATES PATENTS 2,475,996 7/1949' Smith 260-632N 2,978,512 4/1961 Frankel et al 260-632N 3,192,248 6/ 1965 Bonetti et al. 260-632N 3,240,823 3/1966 Bonetti et al. 260-632N 3,410,914 11/1968 Bonetti et al, 260-632N BERNARD HELFIN, Primary Examiner I. E. EVANS, Assistant Examiner US. Cl. X.R. 

